Translation Memory (TM) technology has been enjoying a good deal of popularity among translation theorists and practitioners since it came onto the market in the 1990s. A theoretical framework for TM vis-à-vis Machine Translation (MT) is first discussed. The paper then examines the applicability of a TM tool, namely Translator’s Workbench (TWB), to Arabic, and the ensuing problems as illustrated by the translation output of ten postgraduate translation students at Al-Quds University for the academic year 2012/2013. The paper reveals that beyond the translation problems with which translation is usually replete, particularly between languages of little cultural and linguistic affinity, e.g., Arabic and English, the students encounter several problems arising from the inherent structure of TWB. The study concludes by assessing some of the pedagogical implications of these difficulties, in a way that will hopefully help Computer-Assisted Translation (CAT) trainers deal with the problems in future.